Cryogenic Separation Of Glauconite And Foraminifera From The Cretaceous/Paleogene Boundary Interval At Nasiłów, Poland, For Radiometric Dating And Stratigraphy

We have demonstrated that cryogenic separation of glauconite and foraminifera from the host rock allows to preserve the integrity of extracted specimens, assures minimal damage and causes no artificial fractionation. The K/Ar dating of two glauconite samples from Cretaceous/Paleogene boundary in the Nasiłów outcrop yields 62.0 and 66.3 Ma. The discrepancy in these dates, much larger than expected from analytical precision, may result from too low %K, which was 5.91 and 5.73, respectively.

Space-Time Curvature Of General Relativity And Energy Density Of A Three-Dimensional Quantum Vacuu

A three-dimensional quantum vacuum condensate is introduced as a fundamental medium from which gravity emerges in a geometro-hydrodynamic limit. In this approach, the curvature of space-time characteristic of general relativity is obtained as a mathematical value of a more fundamental actual variable energy density of quantum vacuum which has a concrete physical meaning. The fluctuations of the quantum vacuum energy density suggest an interesting solution for the dark energy problem.

Carbon Isotopic Composition Of Earlydiagenetic Methane: Variations With Sediments Depth

We demonstrate the annual cycle of methane in fresh sediments of two lakes - Moszne (E Poland) and Skrzynka (W Poland). The vertical gradient in δ

δ37Cl of waters from the Akyatan Lagoon, Turkey

We report the first δ

A Cycle Of Enzymatic Reactions With Some Properties Of Neuronal Circuits

A cycle of four methylation and four demethylation reactions with repression or allosteric inhibition of enzymes is considered. The corresponding dynamical system is characterised by two parameters: the sum of reagent concentrations (C) and the ratio of rate constants of forward and backward reactions (k). In a symmetrical case (k=1) the system has a unique equilibrium. At C>4 the equilibrium is unstable and the system has oscillatory solutions. At k essentially different from 1, the system becomes excitable or behaves as a bistable trigger.

Positive And Negative Feedback Loops Coupled By Common Transcription Activator And Repressor

Dynamical systems consisting of two interlocked loops with negative and positive feedback have been studied using the linear analysis of stability and numerical solutions. Conditions for saddle-node bifurcation were formulated in a general form. Conditions for Hopf bifurcations were found in a few symmetrical cases. Auto-oscillations, when they exist, are generated by the negative feedback repressive loop. This loop determines the frequency and amplitude of oscillations. The positive feedback loop of activation slightly modifies the oscillations. Oscillations are possible when the difference between Hilll’s coefficients of the repression and activation is sufficiently high. The highly cooperative activation loop with a fast turnover slows down or even makes the oscillations impossible. The system under consideration can constitute a component of epigenetic or enzymatic regulation network.

Isotope Geochronology: Models Versus Reality

Majority of the papers on isotopic dating of minerals and rocks have been devoted to some new geochronological data important for geology or to developments of apparatus and improvements of laboratory techniques and procedures. However, there are some basic problems concerning credibility of the data published (including the “error brackets”), and their geological meaning, which rarely are touched on. The issues to be raised may be grouped into two categories: (1) distortion in the course of preparatory operations and final measurements, and (2) some doubts concerning geological interpretation of the data and the models used. First of all it should be realized that what we really analyse in a spectrometer is not an existing rock or mineral but a powder produced by many steps of consecutive procedures, each of them capable of irreversibly distorting the original composition.

Radial Distribution Of Stars In Globular Clusters Inferred From The Monte Carlo Approach

In this paper we try to reconstruct the spatial distribution of stars in globular clusters (GCs) from heuristic statistical ideas. Such 3D radial distributions are important for understanding physical conditions across the clusters. Our method is based on converting spherically symmetrical functions such as exp(-r